With increased interest in problems of air pollution, particularly as to pollutants caused by combustion of hydrocarbons, there has been a rapid increase in the research directed to improved gas sampling apparatus. Apparatus for determining the content of a specific component in a sample stream is, ideally, designed to be responsive only to the component of interest. Unfortunately, such apparatus often responds not only to the component of interest, but to various "contaminants"0 as well. Where such contaminants exist within the sample stream, they must be removed, neutralized, or their effects masked. Since much of the gas being tested is the atmosphere which we breathe and the atmosphere often contains numerous hydrocarbons, these hydrocarbons become one of the major contamination sources. They need to be measured in the exhaust emissions of automobiles as well, in order to improve fuel efficiency and minimize emissions. According to the guidelines established by the Environmental Protection Agency, methane is the only nonreactive hydrocarbon; all others are considered reactive hydrocarbons. Presently, methane is analyzed either by a gas chromatograph using flame ionization detection, an infrared analyzer, or by selective thermal cracking of other hydrocarbons. Gas chromatographic analysis is not continuous, requires at least five minutes for each analysis cycle, and is, therefore, not suitable for modal analysis in automobile engine research and development. Infrared analysis, by its very nature, is not selective in spite of the extreme refinements in detectors and optical filters used, as serious interference occurs from other hydrocarbons. Selective thermal cracking is claimed to yield non-quantitative data due to the changing nature of the catalyst.
Accordingly, it is the object of the present invention to provide a reactor capable of removing the effects of all hydrocarbons from a gas sample stream or all hydrocarbons except methane, to provide apparatus for removing hydrocarbons as contaminants from a gas sample stream or, alternatively, to provide the ability to test for methane content as an item of interest within the gas stream.
It is a further object of the present invention to provide a reactor capable of removing the effects of a family of contaminants from a gas sample stream being used by gas analysis apparatus for the determination of specific components of the gas sample stream.